The plasma cell disorders are monoclonal neoplasms related to one another by virtue of their development from common progenitors in the B-lymphocyte lineage. Included in this group of plasma cell disorders are multiple myeloma, Waldenstrom's macroglobulinemia, and primary amyloidosis (Harrison).
Under normal circumstances, maturation to antibody-secreting plasma cells is stimulated by exposure to the antigen for which the surface immunoglobulin is specific. However, in the plasma cell disorders the control over this process is lost.
Multiple myeloma represents a malignant proliferation of plasma cells. The disease results from the uncontrolled proliferation of plasma cells derived from a single clone. The tumor, its products, and the host response to it result in a number of organ dysfunctions and symptoms of bone pain or fracture, renal failure, susceptibility to infection, anemia, and other symptoms.
The vast majority of patients with myeloma require therapeutic intervention, and chemotherapy is one common therapy. Conventional chemotherapy can be effective against the malignant plasma cells in the bone marrow, but is often ineffective in killing the regenerative blood-borne B cells which are responsible for patient relapse, as the malignant B cell population often become multidrug resistant, making treatment difficult. It has recently been shown that the malignant B cell population is responsible for repopulating the bone marrow and causing patient death (Pilarski).
The leukemias are a heterogeneous group of neoplasms arising from the malignant transformation of hematopoietic cells. Leukemic cells proliferate primarily in the bone marrow and lymphoid tissues where they interfere with normal hematopoiesis and immunity. Ultimately they emigrate into the peripheral blood and infiltrate other tissues (Harrison).
Leukemias are classified according to the cell types primarily involved, myeloid or lymphoid, and as acute or chronic based upon the natural history of the disease. Acute leukemias have a rapid clinical course, resulting in death within a matter of months without effective treatment.
Acute lymphocytic leukemia is one example, where approximately 60 percent of acute lymphocytic leukemia cases are common acute lymphocytic leukemia, where the cells are Tdt-positive and have the common acute lymphocytic leukemia antigen but do not express surface membrane immunoglobulin or T-cell antigens. These cells are usually derived from precursors of the B-cell lineage.
About 20 percent of acute lymphocytic cases are of the T-cell type, where the T-lymphoblasts express the E-rosette receptor or other T-lymphocyte related antigens. T-cell acute lymphocytic leukemia usually occurs in adolescent males and is associated by a high leukocyte count and an anterior mediastinal mass.
The malignant lymphomas, in contrast to leukemias, are neoplastic transformation of cells that reside predominately in lymphoid tissues. Non-Hodgkin's lymphomas are derived from both B-cell and T-cell origins (Harrison), where 90% of all cases of non-Hodgkin's lymphomas are of B-cell derivation and the remaining 10% are of T-cell derivation.